Interest Cost:

(total interest cost over the life of the loan)

Total Cost of Loan:

(interest + principal loan amount)

Amortization.

Loan amortization is the process of paying back a loan over an extended duration of time along with the interest incurred. The interest to be paid for the amount borrowed, till the loan is completely repaid, is calculated in advance. This is divided by the total number of payments being made and added with the principal payments to arrive at an amount that consists of both the principal as well as the interest. The payments have to be made according to this amortization schedule, which is decided before the loan is issued and could be in the form of simple monthly or annual payments. Before the principal amount is issued, the terms for calculation of the interest are also fixed.

Each time you make a payment on a loan you pay some interest along with a part of the principal. The principal is the original loan amount, or the balance that you must pay off. By making regular periodic payments, the principal gradually decreases, and when it reaches zero, you've completely paid off your debt.